The present invention relates in general to a seat assembly for a motor vehicle. More particularly, the present invention relates to a pivot assembly for a structured vehicle seat of the type that carries a retractable safety belt and includes a seatback pivotally interconnected to a lower seat structure. The pivot assembly is configured to transfer the potentially significant safety belt loads that may be incurred during severe deceleration or vehicle collision from the seatback to the lower seat structure, and in turn, to the vehicle frame.
Virtually all motor vehicles are equipped with restraint systems including a retractable safety belt for physically restraining a seat occupant when the vehicle is subjected to a high rate of deceleration which may occur, for example, during a vehicle collision or during severe braking. In conventional vehicles, the retractable safety belts are predominantly attached directly to the vehicle structure. For example, most modern safety belt systems utilize a belt retractor mounted to the vehicle floor pan which adjustably receives the retractable belt. The retractable belt extends upward from the belt retractor along the B-pillar of the vehicle to a guide ring mounted to the B-pillar. The retractable belt then extends downward from the B-pillar guide ring adjacent to the belt retractor where an end of the retractable belt is connected to the vehicle floor. A tongue plate is mounted on the safety belt and is slidably movable therein between the end anchored to the vehicle floor and the guide ring on the B-pillar. A buckle is interconnected with the vehicle floor on the opposite side of the occupant seat.
When the tongue plate is pulled across the occupant and releasably inserted into the buckle, the retractable belt forms a lap belt portion across the occupant's midsection and a shoulder belt portion extending diagonally across the occupant's torso. The lap belt portion and shoulder belt portion cooperate to retain the occupant in the seat. While mounted to the vehicle frame independently from the seat, the safety belt restraint system is intended to be positioned in such a proximity to cooperate with the seat for effectively and comfortably restraining the seat occupant during severe deceleration.
While conventional safety belt restraint systems, such as the type described above, have proven to be commercial acceptable for many applications, each is attendant with drawbacks and subject to improvement. In many applications, the operation and comfort of such a conventional safety belt restraint system conflicts with the operational requirements of modern vehicle seat assemblies. In this regard, virtually all modern vehicles are equipped with seating assemblies that can be selectively adjusted in at least the fore and aft direction for providing increased comfort and convenience to the seat occupant. Furthermore, modern vehicle seat assemblies, particularly those intended for front seat applications, are almost exclusively constructed to include a seatback mounted for pivotal movement relative to a seat cushion for selective articulation between a generally upright position and a fully reclined position.
Through conventional adjustment of a seat assembly in the fore or aft direction, an occupant seated on the seat assembly is effectively translated relative to the mounting points (i.e, belt retractor, B-pillar guide ring, belt end connection, and tongue plate) of the safety belt restraint system. As a result, it frequently becomes inconvenient and uncomfortable for a seat occupant to correctly employ and/or utilize the safety belt restraint system, thereby often discouraging use of the safety belt restraint system. For example, if the vehicle seat assembly is selectively moved to a forwardmost position, it is often difficult for the seat occupant to reach back to grasp the seat belt tongue plate carried adjacent the B-pillar. This difficulty is particularly true with elderly occupants, occupants with physical disabilities and occupants of smaller physical stature. Furthermore, when the position of the vehicle seat assembly is forwardly adjusted, the shoulder belt portion of the retractable belt may abrade the seat occupant's neck, thereby resulting in occupant irritation or discomfort.
Other difficulties and problems are encountered when a conventional seat assembly is adjusted to its rearwardmost position. For example, the shoulder belt portion of the retractable belt is more susceptible to slight displacement from the upper torso of the restrained occupant. As a result, the occupant may be undesirably permitted to momentarily shift forward unrestrained by the shoulder belt portion of the retractable belt when the vehicle is subject to severe deceleration forces. Similar inconveniences are encountered by the vehicle occupant when the seatback is pivotally articulated from a standard operating position towards its fully reclined position. Furthermore, a restrained seat occupant having the vehicle seat in the rearwardmost position may be unable to move the seat to a more forward position without first readjusting the retractable belt.
The noted difficulties and inconveniences associated with conventional seat assemblies and safety belt restraint systems are further complicated in seating applications for convertible vehicles. In this regard, for obvious reasons, it is desirable for convertible vehicles to eliminate an upwardly extending B-pillar. As a result, the upper B-pillar mounting point for the retractable belt is often inconveniently positioned relative to the seat occupant, frequently resulting in less than ideal belt fit and occupant discomfort.
It is also known to mount a safety belt restraint system directly to a seat assembly. In such an arrangement, the structure of the seat assembly must be of sufficient strength to accommodate the potentially significant loads that may be generated as a result of vehicle deceleration from impact, severe braking, or the like. However, known "structured" seat assemblies have also been associated with various disadvantages. The primary problem with such known constructions resides in an inability to efficiently and effectively transfer deceleration loads received by the seatback to the vehicle structure. More specifically, known constructions for structured seat assemblies have been unable to fully retain the operation features (e.g., pivotally mounted seatback, fore and aft translation, etc.) demanded by consumers without utilizing complex arrangements for pivotally mounting the seatback to the lower seat structure. When functionally acceptable, these complex arrangements are often weight prohibitive, cost prohibitive, or both.
In view of the foregoing, a need clearly exists to develop a pivot assembly for vehicle seat assembly having a structured frame for absorbing loads received from an attached safety belt restraint system and transferring such loads to the vehicle frame. More specifically, a need exists to develop a vehicle seat assembly which efficiently and effectively overcomes the known shortcomings associated with vehicle seat constructions and yet which can be readily adapted for use in various vehicular seating applications.